1. Filed of the Invention
The present invention relates to an optical assembly having three optical sources each corresponding to the three primary colors, and a method to assemble the optical assembly.
2. Background Arts
Flat panel displays have been so popular in the consumer market, and a trend to apply the displays to mobile communications has advanced. One type of flat panel displays installs laser diodes, which is superior in aspects of the power consumption, the definition, and the saturation compared with those implementing with white LEDs (Light Emitting Diode) as an optical source of the backlight of the display. Accordingly, the flat panel display implementing with LDs is going to be applied to, for instance, small sized projectors, head-mount displays, head-up displays, and so on. Such an optical source implements with three LDs, namely, a red LD, a green LD, and a blue LD, corresponding to the three primary colors. High quality image with the superior saturation may be achieved by mixing laser light emitted from respective LDs as modifying amplitudes thereof.
In order to mix three colors, wavelength selective filters and other optical components to guide the mixed light to an optical apparatus, such as MEMS (Micro Electro-Mechanical System), DLP (Digital Light Processor), LCOS (Liquid Crystal On Silicon) and so on, are needed. When three LDs and other optical components are installed within an optical module, an extremely precise optical alignment of the LDs and the components is inevitable because the LDs operate as a point optical source but the far field pattern thereof is necessary to be set narrower, for instance, the far field pattern of 10°×20° is necessary. When three LDs are independently packaged and the optical system to guide light to those apparatus are prepared outside of the LD packages, the total size of the system to provide the three primary colors becomes large.